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Comment by tlrobinson | Hacker News Reader

True, but the existing Node APIs don't do that, they return the error as an argument to the callback.

The wiki page says:

    // these two lines are equivalent
    await a, b, c, d = moo(1, 2, 3);
    moo(1, 2, 3, function(a, b, c, d) {} );

So I don't see why not...

    // ...these two lines would be also equivalent
    await error, foo = bar(1, 2, 3);
    bar(1, 2, 3, function(error, foo) {} );

Exactly. The error object is a return value of the "await"-ed function, not an exception that's thrown.

Here's a concrete example. Normally in Node you do something like this:

  fs.readFile('/etc/passwd', function (err, data) {
    if (err) {
      // handle error
    }
    // normal processing
  });

The await version would look like this:

  await err, data = fs.readFile('/etc/passwd');
  if (err) {
    // handle error
  }
  // normal processing

Ideally it would look like this:

  try {
    await data = fs.readFile('/etc/passwd');
    // normal processing
  } catch (error) {
    // handle error
  }

This is certainly something that is doable and crossed my mind, but I did not want to have the await be restricted to functions that conform to the typical return arguments. For now at least.

How about

  try await foo = bar(baz)

as shorthand for

  await error, foo = bar(baz)
  if (error) throw error

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